Squirrel proof Bird feeder

Since moving to our chalet on the river we have often been entertained by the many Eastern Gray Squirrels that frequent our deck and bird feeders. The little rascals not only eat the corn that we put out for them but insist on eating suet and bird seed out of feeders as well. They have ruined a couple of feeders by chewing through the hard plastic to get to the seeds. We bought a metal "Squirrel proof" feeder and had many a chuckle watching the squirrels try to figure a way to get to the seeds. They would get on top and reach over the sides which usually resulted in a fall or a slip. It wasn't long however, that at least one of them began hanging upside down with it's hind feet and reaching up with the forefeet to get at the seed tray without tripping the gate. This behavior finally got one squirrel in trouble. The other morning while eating breakfast and watching the squirrel hanging from it's bird feeder perch we watched in amazement as a mature Red-tailed Hawk swooped down from a perch and plucked the squirrel off of the feeder without missing a wing beat. The other squirrels on the ground scrambled in all directions. The hawk flew to a nearby tree where it perched moitionless for a couple of minutes with the squirrel grasped firmly in it's fist, It's brilliant rusty red tail contrasted dramatically with the dark burnt sierra brown of the body and wing feathers. Then it lifted off with the squirrel clutched in one foot to a perch high on the other side of the river. There the squirrel was ripped open by the strong sharply curved beak of the raptor and eaten piece by piece. This is unusual behavior for a large Buteo but during the cold winter months they are opportunistic,clever and inventive when foraging.
They use the still perching method much like the Great-horned owl, sitting moitionless until their prey is spotted then swooping stealthfully down for the suprise attack. It happened so fast the squirrel had no clue what hit him .
That day and the day after there were no squirrels to be seen.
On the third day I noticed one that seemed a bit more wary than usual. It will be interesting to see if any of the other squirrels take up the habit of hanging upside down. If they do I hope to be waiting with camera ready.